Hi,

I recently purchased a NerdKit to build the OBD II project posted on your website (http://www.nerdkits.com/videos/obdii/). I found an OBD II pinout diagram online (http://www.interfacebus.com/OBDII-pinout-signal-assingment.html), and I'm a little confused by the difference between pins 4 and 5. Pin 4 is a chassis ground, and pin 5 is a signal ground. Is it safe to connect both of these lines to the negative bus on a breadboard? If so, then why are they two separate pins?

Thanks, Zach